October 29, 2003: Duck!

One of the most powerful solar flares ever recorded erupted yesterday morning near giant sunspot 486. The explosion hurled a coronal mass ejection (CME) directly toward Earth. Bright auroras could appear when the fast-moving cloud sweeps past our planet. High-latitude sites such as New Zealand, Scandinavia, Alaska, Canada and US northern border states from Maine to Washington are favored, as usual, but auroras could descend to lower latitudes, too.

Not all CMEs trigger auroras. Several, for instance, have swept past Earth in recent days without causing widespread displays. It all depends on the orientation of tangled magnetic fields within the electrified cloud of gas. This CME is no exception. It might cause auroras, or it might not. We will find out when it arrives.